EP 0 897 788 A1 describes a method for forming a corrugated and thermally-insulated conduit. Conduits of the aforementioned type prepared by this method have proven their worth. A further improvement of the method is known from WO 2010/085906, in which a deeper corrugation can be achieved, whereby a conduit having a corrugation is explicitly shown, which has a U-shaped groove in the outer housing and the insulating layer, respectively, between straight running segments. The corrugation depth is 4 mm to 10 mm and a better flexibility of the conduit can be achieved. The good flexibility of a conduit makes it possible to roll-up a greater delivery length onto a conduit feed roll, which is advantageous for the logistics expenses. Moreover, the effort may be lower during the installation.